The present invention relates to a slot device for installation in a vehicle.
Electronic key systems are used in recent vehicles for anti-theft purposes. A typical electronic key system includes a portable device held by a user (e.g., the driver) and a controller installed in a vehicle. If communication (wide area communication) is established with wireless signals between the portable device and the controller when the user enters the vehicle while holding the portable device, the electronic key system enables starting of the engine. More specifically, an ID code of the portable device is compared with an ID code of the controller. When the two ID codes are identical, the controller enables starting of the engine.
The portable device includes a communication circuit for communicating with the controller and a battery for supplying the communication circuit with power. To enable communication between the controller and the communication circuit when battery drainage occurs, the portable device further includes a transponder. The transponder is activated by electromagnetic energy, which is generated by a wireless signal transmitted from the controller, to transmit an ID signal, which includes an ID code, and enable communication (narrow area communication) in an area narrower than the area in which wide area communication is performed.
A slot device is arranged near the driver seat in the vehicle. The controller outputs the wireless signal when the portable device is inserted in the slot device. Thus, when battery drainage occurs in the portable device, the portable device is inserted in the slot device to activate the transponder and enable communication between the portable device and the controller. Japanese Laid-Open Patent Publication No. 2004-058731 describes such a slot device.
The slot device includes a case, which has an opening, and a shutter, which covers the opening of the case. The shutter is movable along the inner surface of the case. A cylindrical spring receptacle, which has an open end, projects from the inner surface of the shutter. The spring receptacle receives and supports one end of a coil spring. The other end of the coil spring is received and supported by a guide, which projects from the surface of the case facing toward the shutter. Thus, when inserting the portable device in the case, the shutter moves inwardly into the case with the portable device against the urging force of the coil spring. When the portable device is removed from the case, the urging force of the coil spring returns the shutter to the position where it closes the opening. A stopper is arranged at the inner side of the opening. The shutter abuts against the stopper when closing the opening. In this state, the shutter is flush with the outer surface of the case around the opening.
To smoothly compress and expand the spring, a clearance (gap) is provided between the outer surface of the spring and the inner surface of the spring receptacle. However, if the slot device is located, for example, near the gearshift lever, vibrations produced when shifting the gearshift lever may be transmitted to the coil spring. In this state, if the portable device is not inserted in the slot device, this may produce noise (rattling).
To prevent the coil spring from being vibrated by externally transmitted vibrations, for example, the spring force (urging force) of the coil spring may be increased. As a result, the two ends of the coil spring would apply a strong force to the opposing surfaces of the spring receptacle and the case. This would prevent the coil spring from vibrating. However, a strong force would be required to insert the portable device in the slot device. Further, this may cause the portable device to pop out of the slot device during removal and affect the convenience of the slot device.
To prevent the coil spring from vibrating without increasing the force of the coil spring, grease may be applied to the coil spring. This would cause the coil spring to be viscid and prevent the coil spring from vibrating. However, when inserting the portable device in the slot device, grease may stick to the portable device. Normally, the user would remove the portable device from the slot device when leaving the vehicle. The user may then put the portable device into a clothing pocket or a bag. As a result, the grease may stain the user's clothing or bag or cause the portable device to slip in the user's hand. This would affect the convenience of the slot device.